Snap action device



Jan. 9, 1962 R. R. TARBUCK SNAP ACTION DEVICE Filed Jan. 22, 1960 JNVENTOR.

ROBERT R. TARBUCK BY ATTORNEYV u 4 o 8 2 w 3,016,433 SNAP ACTION DEVICE Robert R. Tarbuch, West Chester, Pa., assigner to Burronghs Corporation, Detroit, Mich., a corporation of Michigan Filed lan. 22, i960, Ser. No. 4,034 Claims. (Cl. 20G-67) This invention relates generally to snap action devices and more particularly to devices of this type which are incorporated in electrical switches.

An object of the invention is to provide a snap action device of simple construction and few parts.

Another object of the invention is to provide a structure of the snap action type which is capable of being actuated to any one of three conditions by the manipulation of a single control member.

A further object of the invention is to provide such a structure having particular utility in electrical switches.

In accordance with the above objects and considered first in its broad aspects, the invention comprises a spring element having stressed areas and assuming in this condition a neutral position of equilibrium. When a force is applied to the spring element in a given direction, one of the stressed areas is caused to resume its normal shape and in so doing causes the spring element to respond by a snap action movement and to assume a second condition of equilibrium. When a force is exerted against the spring element in the opposite direction, a similarV action will occur and the spring element will be caused to assume a third-condition of equilibrium.

The invention will be more fully understood when the following detailed description of a specific embodiment thereof is read in conjunction with the accompanying drawings in which:

FIG. l is a side elevational view of an electrical switch structure constructed in accordance with the invention;

FIG. 2 is a sectional View taken on llne 2 2 of FIG. 1;

FIG. 3 is an enlarged sectional View of a fragmentary portion of FIG. 2;

FIG. 4 is an enlarged sectional View taken on line 4 4 of FlG. 2;

FIG. 5 is a broken developed view of a spring actuator member;

FIG. 6 is an enlarged fragmentary sectional View taken on line 6 6 of FIG. 2; and

FiGS. 7 and 8 show diierent actuated conditions of the switch structure.

As seen in the drawings, one embodiment of the invention includes a supporting frame or housing 8 of insulating material and lcomprising a base member 10 and a cap l2 secured to the base member by means of screws 14.

Secured in the base member It) are electrical contacts 16 and i8 and a metallic bushing 20. Each of the contacts lr6 and 1S and the bushing 20 are provided with screws 22, 24 and 26 respectively, for attaching or connectin a conductor wire of an electric circuit.

Secured to the bushing 20 by means of a screw 28 is an inverted U-shaped contact member 3i) havingthin spring contact arms Stia and 3011 which carry'respectively at their free ends contacts 32 and 34.

The cap l2 is provided with an elongated rectangular transverse aperture 36 (FlG. 6) through which extends a spring actuator 38. The horizontal edge portions of aperture 36 are suitably rounded and the height of the aperture 36 suitably chosen to permit the snap action movements of the actuator 38, as will be seen more clearly hereinafter.

rthe actuator 38 is formed of an elongated strip of thin spring leaf material (FIG.5) having a concave-convex cross section and in this preferred form of the invention Patented dan. 9, M1362 is doubled back upon itself, as shown in FIG. 2, with its convex surface facing outwardly. As thus formed the actuator 38 comprises a looped portion 38a interconnecting a pair of elongated strips or actuating arms ib and 33C. The ends of the actuating arms 3817 and 38e are similarly provided with perforations 4d and 42 (FIG. 5) and open connecting slots 44 and d6. A grommet 4S (FiG. 4) of an insulating material such as rubber, for example, is pushed through the aligned slots 44 and 46 and into the perforations 4d and 42 to secure together the ends of the actuating arms 3511 and 33C, as shown in FIG. 2. A screw 56 threadedly secured in the cap 12 extends through the aperture 36 and with ample clearance through aligned perforations 52 and 54 in the actuating arms 3817 and Stic thus to movably anchor the actuator 38 to the cap 12.

In the region 56 where the actuating arms SSI; and 38C merge with the looped portion 33a, the actuating arms will not have a concave-convex cross section when in the condition shown in FIGS. 2 and 3, but will be kinked or stressed into a substantially at or planar cross-sectional form, as seen in FIG. 6. Accordingly, when pressure is exerted downwardly on the upper surface of the looped neutral position of FIG. 2 to a point where the stress in the kinked portion (FIG. 3) of the actuating arm 38b will suddenly release thus allowing the actuating arm 38b to snap to its full concavo-convex form to the extent indicated by the line K, FIG. 7, thus causing the actuating arms 38h and 33C to snap downwardly as a unit and close the contacts 34 and i6. If it is desired to close the contacts 32 and I8, pressure is exerted upwardly on the lower surface of the looped portion 38a Vand a similar snap action will occur in the opposite direction, as illustrated in FIG. 8, in which case the actuating arm 38e will snap to its full concave-convex form to the extent indicated by the line K'.

By exerting sutlcient pressure on the looped portion 38a, the actuator 3S can be transferred directly from one contact position to another, as from its position in FiG. 7 to its position in FIG. 8, or by exerting a lesser degree of pressure the actuator 38 can be returned to the neutral position of FIG. 2.

It will now be seen that the invention provides a tristable snap action device particularly suitable for electric switch structures. While for purposes of illustration the actuator has been shown in a switch structure in which its function is to close electrical contacts, it is understood that the actuator itself may be a circuit element closing its own contact and in such a construction it would be the sole moving part. t

While there has been shown a specific structure exemplifying the principles of the invention, it is to be understood that this is but one embodiment thereof and that the invention is capable of being constructed in a variety of shapes, forms and modifications without departing from the true spirit and scope thereof. Accordingly, it is to be understood that the invention is not to be limited by the specific device disclosed but only by the subjoined claims.

What is claimed is:

l. In a snap action device, the combination comprising, a pair of elongated strips of concavo-convex spring material extending in a first equilibrium position and secured together at one end with their convex surfaces facing outwardly, said elongated strips being stressed to a nonconcavo-convex cross section at their other end portions, a member pivotally mounting said other end portions,

and means for applying a. force to said other end portions 3 said elongated strips to rock about said member and assume a second equilibrium position.

2. in a snap action device, the combination comprising, a pair of elongated strips of concavo-convex spring material extending in a first equilibrium position and secured together at one end with their convex surfaces facing outwardly, said elongated strips being stressed to a nonconcavo-convex cross section at their other end portions, a iixed member loosely pivoting said other end portions, and means connecting said other end portions and being movable to cause the stressed region of one of said elongated strips to resume a concave-convex cross section and to cause said elongated strips to rock about said xed member and assume a second equilibrium position.

3. in a snap action device, the combination comprising, an elongated strip of concave-convex spring material, said elongated strip being doubled back upon itself with its convex surface facing outwardly to form a loope portion and substantially parallel actuating arms extending from said looped portion and being in a first equilibrium position, said doubling back imposing a stress in said actuating arms in the region adjacent to said looped portion, means for securing together the free ends of said actuating arms, and a member movably securing said doubled-back strip adjacent to said looped portion, and wherein the stress in one of said actuating arms will be relieved and said doubled-back strip will respond with a snap action movement on said member and assume a second equilibrium position when a force is exerted on the side of said looped portion from which extends said one of said actuating arms.

4. in a snap action device, the combination comprising, an elongated strip of concavo-convex spring material having spaced apart apertures along its longitudinal dimension, said elongated strip being doubled back upon itself with its convex surface outwardly and said apertures in alignment, -said 'doubled-back strip having a looped portion adjacent to said apertures and substantially parallel actuating arms extending from said looped portion in a first equilibrium position, said doubling back imposing a stress in said actuating arms in the region of said apertures, means for securing together the free ends of said actuating arms, and a xed member freely received through said apertures, and wherein the stress in one of said actuating arms will be relieved when a force is exerted on the side of said looped portion from which eX- tends said one of said actuating arms to cause said actuating arms to snap into a second equilibrium position.

5. An electrical switch structure of the snap action type comprising, a supporting frame, an electrical Contact carried by said supporting frame, a pair of elongated strips of concave-convex spring material secured together at one end with their convex surfaces facing outwardly, said elongated strips each having an aperture at their other ends andeach having a stressed region adjacent to said apertures, a member fixed to said supporting frame and freely received through said apertures for movably anchoring said actuating arms to said supporting frame, and means connected to the apertured ends of said actuating arms and being movable to relieve the stress in one of said actuating arms to cause said actuating arms to respond by a snap action movement and close a circuit containing said electrical contact.

'Reerences Cited in the fiile of this 'patent UNITED STATES PATENTS 

